The present disclosure relates to a developing device and an image forming apparatus.
In general, a developing device of an electrophotographic system includes a storage portion that stores developer, a developer carrying member of a cylindrical shape, a magnet disposed in a hollow portion of the developer carrying member, a stirring portion configured to stir the developer, and a layer thickness restricting portion configured to restrict the layer thickness of the developer on the developer carrying member.
The stirring portion is of a screw feeder type and includes a shaft portion and a blade portion spirally extending outward from the shaft portion. The developer carrying member is referred to as a magnetic roller, a magnetic sleeve or the like.
It is known that, on the surface of the developer carrying member, streaky density unevenness of the developer may be formed along the blade portion of the stirring portion. In particular, in a case where the developer includes toner of a low-melt-type whose melting point is low, the density unevenness is likely to occur due to the stirring portion.
In addition, it is known that a restriction plate facing the outer circumferential surface of the developer carrying member may be provided on the upstream side of the layer thickness restricting portion in the rotation direction of the developer carrying member, and that a projection portion is formed on the surface of the restriction plate.
The restriction plate compresses the developer carried by the developer carrying member by gradually narrowing the passage of the carried developer. The projection portion moderates the density unevenness of the developer on the outer circumferential surface of the developer carrying member.